1. Field of the Invention
The present invention relates to a fluid compressor and, more particularly, to a fluid compressor for compressing a refrigerant gas or the like used for a refrigeration cycle.
2. Description of the Related Art
For example, U.S. Pat. No. 4,871,304 discloses a fluid compressor designed to compress a fluid while transferring it.
As shown in FIG. 13, a compressor 1 of this type has a compression mechanism 3 and a motor 4 housed in a sealed case 2. In the compression mechanism 3, a rotating member 6 is eccentrically disposed in a cylinder 5, and the cylinder 5 and the rotating member 6 are supported by a main bearing 7. The main bearing 7 is fixed to the inner wall of the sealed case 2.
The two axial end portions of the cylinder 5 are respectively sealed by the main bearing 7 and a sub-bearing 8. A main shaft 9 and a sub-shaft 10 are respectively formed on the two axial end portions of the rotating member 6. The main shaft 9 and the sub-shaft 10 are respectively inserted into the bearings 7 and 8.
A spiral groove 11 is formed in the rotating member 6. The pitch of the groove 11 is gradually decreased as the groove 11 extends from one end to the other end. A spiral blade 12 is fitted in the groove 11 so that the space between the rotating member 6 and the cylinder 5 is partitioned into a plurality of regions by the blade 12. A plurality of operating chambers 13 are formed in the cylinder 5. The volumes of these operating chambers 13 are gradually decreased from one end to the other end, i.e., from the suction side to the delivery side of the cylinder 5.
The motor 4 is constituted by an annular stator 14 and an annular rotor 15. The stator 14 is fixed to the inner wall of the sealed case 2, whereas the rotor 15 is disposed inside the stator 14. In addition, the rotor 15 is fixed to the outside of the cylinder 5 so that the rotor 15 and the cylinder 5 are integrally rotated upon supplying a current to the motor 4. The rotational force of the cylinder 5 is transmitted to the rotating member 6 through an Oldham mechanism 16 (to be described later). As a result, the cylinder 5 and the rotating member 6 are relatively and synchronously rotated while their positional relationship is maintained.
Upon relative rotation of the cylinder 5 and the rotating member 6, the blade 12 protrudes/retracts from/into the groove 11 to protrude/retract in the radial direction of the rotating member 6. In addition, refrigerant gas in a refrigeration cycle is drawn into the cylinder 5 through a suction pipe 17 and a suction path 18. The suction pipe 17 is connected to the sealed case 2. The suction path 18 is formed in the main bearing 7.
The refrigerant gas drawn into the cylinder 5 is guided into a suction chamber 19, one of the operating chambers 13 which is located at a position nearest to the suction side. The refrigerant gas is further transferred to a delivery chamber 20, one of the operating chambers 13 which is located at the position nearest to the delivery side. Since the volumes of the operating chambers 13 are gradually decreased, the refrigerant gas is gradually compressed as it is transferred from the suction chamber 19 to the delivery chamber 20.
The compressed refrigerant gas is temporarily delivered into the internal space of the sealed case 2 through a delivery path 21 formed in the main bearing 7. A delivery pipe 22 is connected to the sealed case 2 so that the refrigerant gas in the sealed case 2 is transferred outside the compressor 1 through the delivery pipe 22.
The Oldham mechanism 16 has a rectangular rotating member Oldham portion 23. The rotating member Oldham portion 23 is formed between a rotating member body 24 and the sub-shaft 10. The Oldham mechanism 16 includes an Oldham pin 25 and an Oldham ring 26. The Oldham pin 25 protrudes inward from the cylinder 5 and is fixed to the cylinder 5. The Oldham ring 26 is slidably engaged with the Oldham pin 25 and the rotating member Oldham portion 23.
The Oldham pin 25 is rotated together with the cylinder 5. The rotating member Oldham portion 23 constitutes part of the rotating member 6 and is rotated together with the main shaft 9, the sub-shaft 10, and the rotating member body 24. The Oldham ring 26 is reciprocated in two orthogonal directions (X and Y directions) upon relative rotation of the cylinder 5 and the rotating member 6.
A sump 27 is formed in the sealed case 2. A lubricant 28 is reserved in the sump 27. Since the high-pressure refrigerant gas fills the sealed case 2, the pressure of the refrigerant gas acts on the lubricant 28. Part of the lubricant 28 is drawn into a lubricant path 29 formed in the sub-bearing 8. The lubricant 28 then flows into the cylinder 5 through a lubricant supply path (not shown) formed in the rotating member 6.
The lubricant 28 is supplied to sliding contact portions in the cylinder 5 (e.g., the portions between the rotating member 6 and the blade 12, the portions between the cylinder 5 and the blade 12, the portions between the cylinder 5 and the bearings 7 and 8, the portion between the main bearing 7 and the main shaft 9, the portion between the sub-bearing 8 and the sub-shaft 10, and the Oldham mechanism 16), thereby lubricating these sliding portions.
In the above-described fluid compressor 1, it is difficult to supply the lubricant to the Oldham mechanism 16. Therefore, a lubricant shortage tends to occur in the Oldham mechanism 16, and the respective parts are easily worn.